It’s maybe not technically labor, but it’s definitely work to be inconvenienced. Last time I was on call, I had to change my lifestyle pretty significantly so that I could drag around a laptop and maintain internet connectivity.
Hiking? Nope. Driving through dead zones? Nope. Going to the movies? Not really. Bike riding? Maybe, if you can hear your phone, haul around a heavy laptop, and stick to areas with phone reception.
Being on call is work. Call it labor or don’t, I don’t care about the semantics. Work is work.
That's why you are being paid for it. Just not your full/standard/normal rate because you are not fully working. You're just available to work in case of emergencies.
Does your salary normally go up in busy (non-overtime) periods during the day?
Or do you, maybe, get paid a general smoothened out curve based on the average for your work expectations over a certain period of time?
You get bonuses, raises, promotions based on how well you perform your job as your salary gets adjusted (ideally at least) according to that (+ end of year bonuses, stock/options, etc). This all also contributes to your total compensation including oncall (which is based on your normal work rates).
Usually how it worked in my team at least, if someone had a tougher-than-usual shift (lots of alerts, large scale incidents, etc) we'd get some extra "rest time" (unofficially) or we'd be told to just take some time off in lieu, etc (on top of your oncall pay already) at discretion of your manager. On the other hand if your team's oncall stats (pager alerts, SLOs metrics, etc) were bad over a long period of time with a lowering trend, you'd have to restructure the way you approach/monitor your system and deal with releases and change management practices because something clearly isn't working. This is all encoded in the principles[0] of what it means to be a good SRE and design good systems and is already taken in consideration as part of your stipend.
Hiking? Nope. Driving through dead zones? Nope. Going to the movies? Not really. Bike riding? Maybe, if you can hear your phone, haul around a heavy laptop, and stick to areas with phone reception.
Being on call is work. Call it labor or don’t, I don’t care about the semantics. Work is work.